The present invention relates to an adaptive interposer and, more specifically, to an adaptive interposer for operable disposition between first and second electronic devices.
A surface mount ceramic device (i.e., an SMD.5 or, more generally, an SMD) typically includes an alumina substrate with a Kovar™ housing and lid and three terminal pads, which are configured to be soldered onto a printed wiring board (PWB). However, since the PWB and the SMD often have different coefficients of thermal expansion (CTE), the PWB and the SMD frequently expand and contract at different rates during thermal cycling. This often leads to cracking in one or both of the PWB and the SMD.
Indeed, it has been seen that substrate cracking of the alumina substrate due to SMD and PWB CTE mismatches can be experienced by the SMD. Such cracking can occur during thermal cycling for SMD.5 assembly processes, in-service environments and user-related environmental exposures in which the SMD and the PWB are both exposed to temperatures ranging from about −55° C. to about 125° C.
Previous attempts to address the problem of substrate cracking in SMD.5 thermal cycling or other similar environments have involved the use of an SMD carrier. The SMD carrier is a leaded ceramic substrate with extended flat copper leads and is sandwiched between the SMD and the PWB to reduce the CTE mismatch and to thereby decrease induced loading. The footprint of the SMD carrier is often relatively large, however, as compared to the SMD device itself, which leads to an efficient use of space on the PWB. Other techniques have made use of a constrained-core PWB having a lower CTE or/and a heat sink attached onto the PWB. However, both of these other techniques tend to increase costs and delivery schedules and may not be applicable for larger sized SMD devices.